Car­vana, a start­up firm offer­ing point-and-click car buy­ing with speedy deliv­ery, is deliv­er­ing used cars with­in a day or two to buy­ers, the same way they might order piz­za deliv­ery. The com­pa­ny has done well in sales in Atlanta, where it start­ed sell­ing cars ear­ly last year. Car­vana will be tak­ing its unusu­al auto sales approach across the South­east region of the US.